Additives for reduction of gun wear



Nov. 1, 1966 M. ROTH 3,282,215

ADDITIVES FOR REDUCTION OF GUN WEAR Filed April 30, 1965 MILTON ROTH United States Patent Ofi 3,282,215 Patented Nov. 1, 1966 ice 3,282,215 ADDITIVES FOR REDUCTION OF GUN WEAR Milton Roth Roclraway, NJ., assignor to the United States of merica as represented by the Secretary of the Army Filed Apr. 30, 1965, Ser. No. 452,408 14 Claims. (Cl. 102-38) The invention described herein may be manufactured and used by or for the government for governmental purposes without payment to me of any royalty thereon.

This invention relates to ordnance items and more particularly concerns inexpensive and readily available chemical additives which are incorporated into cartridges and shells for greatly reducing erosion in gun barrels used therewith.

The problem of excessive gun barrel wear has been a most vexing one because of economy and technical considerations. Jacobson et al., US. Patent No. 3,148,620 deals with the problem at length. However, the problem has not been adequately solved principally due to the generally high cost of their additives employed.

It is therefore a principal object of this invention to economically reduce the erosion in a metal member such as a firearm barrel by incorporating erosion preventive material in the firearm cartridge.

Further objects and advantages will become apparent to those skilled in this art from the appended claims and following description of the invention and exemplifications thereof, made in conjunction with the accompanying drawings showing a preferred exemplary embodiment and wherein:

FIG. 1 is a front elevation view, partly broken away, of a cartridge embodying the preferred additive of the present invention, and

FIG. 2 is a view of an unfolded sheet utilized in the cartridge of FIG. 1.

My metallic temperature and erosion resistant forming substances comprises a salt such as CaSO, or CaCO or either combined with TiO although my inventive additives are not limited thereto, and dispersed in a carbonaceous carrier material such as paraffin or microcrystalline waxes and other hydrocarbons melting between about 70 to 200 F. Excellent results have been obtained using paraffin wax having a melting point between 129.2 F. and l47.2 F., its benzene-insoluble material not exceeding 0.05%. Further, the paraflin shall indicate no acidity or alkalinity and its oil content shall not exceed 0.5% when determined in accordance with ASTM Procedures, D72l-56T.

The part of my inventive sheet comprising the chemical additive or additives dispersed in the wax which is impregnated in a textile adjacent the front part of the charge is more effective than the sheet adjacent the rear end of the charge. Determination of the minimum sheet thickness can be readily computed from the formula set forth in the patent to Jacobson et al supra:

IOVG mgJcm.

where C is the calibre of the firearm in cms.; and cm. refers to the area of the sheet. By sheet, I refer to my additives incorporated or dispersed, whether generally homogeneously or not within the wax carrier, including the textile, fabric or plastic upon which it is coated or impregnated.

The formula given above may be expressed more generally so that it applies to all substances as follows:

30% gram calories per sq. cm. of sheet surfacethat is the substance is such that in reacting with the propellant gases it absorbs 30 gram calories per sq. cm. of the sheet surface.

I have obtained good results by dispersing one of my selected additives in fine particles throughout the wax and applying the mixture on fabric covering the charge.

The preferred form of the invention is illustrated in FIG. 1 wherein a cartridge is shown having a metal case 10, propellant charge 12 comprised of a suitable propellant and a projectile 14. Within case 10 and in contact with the inner surface thereof is a textile wrap 16 which may be of any suitable material such as rayon (preferred) cotton, silk or other conventional materials including plastics, such as polyethylene, for example. The upper section of wrap 16 has a plurality of vertical slits 18 (FIG. 2) through part of its length which form flaps 20 as shown in FIG. 1.

Textile 16 is coated, or coated and impregnated with an additive layer 22 composed of powdered CaSO, or CaCO or Ti0 and CaSO, or TiO and CaCO dispersed in the above-described wax. Other additives to the wax which have been found to perform satisfactorily are white lead, ZnO, ZnS, Sb O salts of alkaline earth metals such as the sulfates, carbonates, oxides, etc. of Mg, Sr, and Ba. It is preferred that the chemical additives be of a very fine particle size, such as that of talc, for example. Flaps 20 and the additive layer 22 are adapted to be folded in overlapping manner over the upper surface of propellant charge 12.

The additive coating is prepared by melting the wax and thereafter mixing with my powdered additive in proportions thereinafter described. Thereafter, the coating is applied to the fabric in the desired thickness and permitted to cool and thus forming my sheet.

Coated fabric 16 which is preferably one-half to fivesixths the length of the charge, may be wrapped around the propellant 12 or it may be held in position in the cartridge as the propellant material is poured in. If desired, fabric 16 may be secured to the inner wall of the case by glue or other suitable means so as to retain the coated fabric in position. Thereafter flaps 20 are folded over and projectile 14 is placed on top of the flaps as shown in FIG. 1.

The following table shows the effectiveness of my inexpensive and readily available additives when tested in mm. high explosive anti-tank shells. My additives have been found to work with equal effectiveness in cartridges and shells ranging from 22 calibre small arms ammunition to 205 mm. shells. The amount and thickness of my additive sheet will depend on the size of the cartridge or shell as aforedescribed. In the data presented below, the textile 16 was a piece of rayon woven from spun viscose rayon yarn containing a durable water repellent of melamine resin base and weighed between 2.80 and 3.20 ounces per square yard. The rayon was placed on a smooth surface and my additives poured thereon and spread evenly by scraping with a blade and resulted in a sheet slightly under l/l6 inch in thickness. of course, it will be understood that other textiles or plastics, as aforementioned, may be used and my additives may be impregnated therewithin as well as produce a coating of specified thickness. The propellant used was triple-based.

In the patent to Jacobson et al., 3,148,620, supra, methods and cartridges are disclosed which reduce gun barrel erosion. My additives reduce gun barrel erosion by about 95% when CaSO is added to TiO and wax. When CaSO and wax are used without TiO which costs about 10 times that of CaS or CaCO I have decreased gun barrel erosion by over 90% and when only CaCO and wax are employed, the reduction is still greater than 85% The cost of the above salts of Ca approximates 3 to cents a pound only and is vastly more inexpensive than other prior art additives which yet yields inferior gun barrel erosion resistance, thus resulting in a tremendous monetary savings to the government since millions of cartridges and shells are manufactured by or for the government annually.

Additionally, the long-sought after need for inexpensive additives to reduce gun barrel wear has existed for many decades and it is apparent from the foregoing description that this need has finally been satisfied.

I claim:

1. In a cartridge having a propellant charge, a projectile, a sheet surrounding at least an upper half of said propellant, said sheet comprising a textile impregnated with a dispersion of a hydrocarbon and a chemical additive selected from the group consisting of 0150;, CaCO a mixture of G280. and TiO and a mixture of CaCO and Ti0 2. The cartridge of claim 1 wherein said hydrocarbon is a microcrystalline wax.

3. In a cartridge having a propellant charge, a projectile, a sheet surrounding at least an upper half of said propellant, said sheet comprising a textile impregnated with a dispersion of paraffin wax and a chemical additive selected from the group consisting of CaSO CaCO a mixture of CaSO and T102 and a mixture of CaCO and TiO 4. The cartridge of claim 3 wherein said paratfin is characterized by a melting point between about 129.2 147.2 F., and its benzene-insoluble material does not exceed 0.05%.

5. The cartridge of claim 3 further characterized by said additive consisting essentially of 10 to 90 weight percent CaSO 6. The cartridge of claim 3 further characterized by said additive consisting essentially of 10 to 90 weight of CaCO 7. The cartridge of claim 3 further characterized by said additive consisting essentially of a mixture of 10 to 40 weight percent TiO and 5 to 80 weight percent CaSO 8. The cartridge of claim 3 further characterized by said additive consisting essentially of a mixture of 10 to 40 weight percent TiO and 5 to 80 weight percent CaCO 9. The cartridge of claim 3 further characterized by said CaSO and paraffin being in the weight proportion of 55 to respectively.

10. The cartridge of claim 3 further characterized by said CaCO and paratfin being in the weight proportion of 45 to respectively.

11. The cartridge of claim 3 further characterized by TiO :CaSO :wax being in the weight proportion of 25:25:50 respectively.

12. The cartridge of claim 3 further characterized by said TiO :CaCO :wax being in the weight proportion of 15:35 :50 respectively.

13. The cartridge of claim 3 further characterized by said TiO :CaC0 :wax being in the weight proportion of 25:25:50 respectively.

14. In a cartridge for use in a gun barrel for reducing erosion thereof upon firing of said cartridge therethrough, a propellant charge within said cartridge, a projectile, a sheet surrounding at least an upper half of said propellant, said sheet comprising a textile impregnated with a dispersion of paraffin wax and an inorganic salt selected from the group consisting of white lead, 811 0 and sulfates, carbonates and oxides of Mg, Ba and Sr, and all combinations thereof, said salts being within the range of about 10 to weight percent and the balance being said wax.

References Cited by the Examiner UNITED STATES PATENTS 943,589 1:2/1909 Bent l0298 l,187,779 6/1916 Patten l0298 2,050,871 8/1936 Woodbridge l0298 2,131,353 9/ 1938 Marsh l0298 2,301,403 11/1942 Hardy l0298 3,009,796 11/1961 Preckel l0298 3,148,620 9/1964 Jacobson et al 102--38 3,204,558 9/1965 Jacobson et al 102-38 BENJAMIN A. BORCHELT, Primary Examiner.

ROBERT F. STAHL, Examiner. 

1. IN A CARTRIDGE HAVING A PROPELLANT CHARGE, A PROJECTILE, A SHEET SURROUNDING AT LEAST AN UPPER HALF OF SAID PROPELLANT, SAID SHEET COMPRISING A TEXTILE IMPREGNATED WITH A DISPERSION OF A HYDROCARBON AND A CHEMICAL ADDITIVE SELECTED FROM THE GROUP CONSISTING OF CASO4, CACO3, A MIXTURE OF CASO4, AND TIO2 AND A MIXTURE OF CACO3 AND TIO2. 